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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. LIGO/Virgo S190814bv: Optical non-detection of radio source AT2019osy from CFHT
  2. Fermi GBM-190816: Eight additional candidates from the Zwicky Transient Facility
  3. GRB 190827A: BALROG localization (Fermi Trigger 588597173 / GRB 190827467)
  4. GRB 190827A: Fermi GBM Final Real-time Localization
  5. LIGO/Virgo S190814bv: DECam-GROWTH detection of an optical counterpart to the radio source AT2019osy
  6. LIGO/Virgo S190814bv: Detection of a candidate radio counterpart with ASKAP
  7. LIGO/Virgo S190814bv: Final list of candidates from the DESGW coadd analysis from the week long search campaign
  8. LIGO/Virgo S190814bv: CFHTphotometryof AT2019npv
  9. LIGO/Virgo S190814bv: SOAR spectroscopy of DECam candidates AT2019npw and AT2019num
  10. LIGO/Virgo S190814bv : Magellan IMACS Spectrum of AT2019npv classified as a Type Ib supernova
  11. GRB 190824A, Swift-BAT refined analysis
  12. LIGO/Virgo S190814bv: SALT optical spectrum of candidate DG19aqbkc
  13. LIGO/Virgo S190814bv: Radio non-detection of DG19wxnjc/AT2019npv with the VLA
  14. GRB 190824A: Swift/UVOT Upper Limits
  15. LIGO/Virgo S190814bv: Keck II NIRES classification of DG19wxnjc/AT2019npv as a stripped envelope supernova
  16. LIGO/Virgo S190814bv: LCO Photometry of DG19wxnjc/AT2019npv
  17. GRB 190823A: Swift-XRT observations
  18. Fermi trigger No 588398821 Global MASTER-Net observations report
  19. LIGO/Virgo S190814bv: MASTER prediscovery and postdiscovery observations DECam candidate DG19wxnjc/AT2019npv field
  20. GRB 190816A: Swift-XRT afterglow detection
  21. LIGO/Virgo S190814bv: No radio counterpart to DG19wxnjc/AT2019npv in ASKAP observations
  22. GRB 190825A: Fermi GBM Final Real-time Localization
  23. GRB 190824A: Swift-XRT refined Analysis
  24. GRB 190824A: Fermi GBM observation
  25. LIGO/Virgo S190814bv: Archival detection of DG19wxnjc/AT2019npv in DES data
  26. Fermi trigger No 588350802 Global MASTER-Net observations report
  27. GRB 190824A: Enhanced Swift-XRT position
  28. Fermi GBM-190816: Updated localization of subthreshold GRB-GW candidate
  29. GRB 190821A: Swift-BAT refined analysis
  30. GRB 190824A: Swift detection of a burst
  31. GRB 190824A: Fermi GBM Final Real-time Localization
  32. LIGO/Virgo S190814bv: Keck NIRES spectroscopy of DG19wxnjc/AT2019npv
  33. LIGO/Virgo S190814bv: Photometric Evolution of DECAM candidates
  34. GRB 190823A: Tiled Swift observations
  35. LIGO/Virgo S190814bv: DESGW photometry of AT2019npv
  36. LIGO/Virgo S190814bv: GROND follow-up observations of AT2019npv
  37. GRB 190823A: MAXI/GSC detection
  38. LIGO/Virgo S190814bv: Further Pan-STARRS z-band observations and AT2019npv photometry
  39. LIGO/Virgo S190814bv: WHT spectroscopy of the host of AT2019npv
  40. Fermi trigger No 588185734 Global MASTER-Net observations report
  41. Fermi GBM-190816: Coverage and upper limits from MAXI/GSC observations
  42. Fermi trigger No 588115134 Global MASTER-Net observations report
  43. GRB 190821A: Swift/UVOT Upper Limits
  44. LIGO/Virgo S190814bv: NIR imaging follow-up of ASKAP transient
  45. GRB 190821A: MASTER VWFC syncronous optical observations
  46. LIGO/Virgo S190814bv: ENGRAVE VLT/HAWK-I observations and archival detection of the CFHT candidate
  47. Fermi GBM-190816: MASTER-Net optical observation report
  48. LIGO/Virgo S190814bv: No radio counterpart detected in ASKAP observations
  49. GRB 190821A: Swift-XRT refined Analysis
  50. LIGO/Virgo S190814bv: a potential faint optical counterpart in CFHT imaging
  51. LIGO/Virgo S190822c: Retraction of GW compact binary merger candidate
  52. LIGO/Virgo S190822c: CLU/NED Galaxies in the 50% Localization Volume
  53. LIGO/Virgo S190822c Global MASTER-Net observations report
  54. LIGO/Virgo S190822c: Upper limits from IceCube neutrino searches
  55. LIGO/Virgo S190814bv: new candidate from DESGW
  56. LIGO/Virgo S190814bv: No Optical Counterpart Candidates in Second-Epoch Lick/KAIT Observations
  57. GRB 190821A: Enhanced Swift-XRT position
  58. GRB 190821A: Fermi GBM observation
  59. Fermi GBM-190816: Upper Limits from Swift/BAT Observations
  60. GRB 190821A: MASTER do not see any afterglow candidate
  61. Fermi GBM-190816: Correction from the Zwicky Transient Facility
  62. GRB 190821A: T60 Les Makes optical detection of the afterglow
  63. Fermi GBM-190816: Four additional candidates from the Zwicky Transient Facility
  64. Swift GRB190821.72 Global MASTER-Net observations report
  65. Fermi trigger No 588100239 Global MASTER-Net observations report
  66. GRB 190821A: Swift detection of a burst
  67. Fermi GBM-190816: No counterpart candidates in Fermi-LAT observations
  68. LIGO/Virgo S190814bv: further candidates from DESGW
  69. Fermi GBM-190816: AGILE in SAA at T0
  70. LIGO/Virgo S190814bv: SOAR spectroscopy of AT2019noq and AT2019ntn
  71. LIGO/Virgo S190814bv: No Counterpart Candidates in Las Cumbres Observatory Galaxy Targeted Search
  72. Fermi GBM-190816: ZTF19abqanpy 10.4m GTC spectroscopy
  73. Fermi-LAT Gamma-ray Observations of IceCube-190819A
  74. LIGO/Virgo S190814bv: AT2019nqq 10.4m GTC spectroscopy
  75. Fermi GBM-190816: One candidate counterpart from the Zwicky Transient Facility
  76. LIGO/Virgo S190814bv: Further Pan-STARRS observations and transient sources
  77. LIGO/Virgo S190814bv: RATIR Optical observations of DECam transients
  78. LIGO/Virgo GBM-190816: no counterpart candidates in the Swift/BAT Observations
  79. Fermi GBM-190816: Upper limits from IceCube neutrino searches
  80. IceCube-190819A: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-190819A: MASTER analysis
  82. IceCube-190819A - HAWC follow-up
  83. Fermi GBM-190816: No counterpart candidates in HAWC observations
  84. LIGO/Virgo S190814bv: No neutrino candidates at Pierre Auger Observatory
  85. Fermi GBM-190816+LIGO/Virgo : no neutrino counterpart candidate in ANTARES search
  86. Fermi GBM-190816: Location-dependent upper limits from INTEGRAL/SPI-ACS prompt observation
  87. Fermi GBM-190816: A subthreshold GRB candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  88. GRB 190816A: Swift-BAT refined analysis
  89. IceCube-190819A: Upper limits from Fermi-GBM Observations
  90. IceCube-190819A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  91. IceCube-190819A - IceCube observation of a high-energy neutrino candidate event
  92. LIGO/Virgo S190814bv: GRAWITA TNG NIR imaging of AT2019nqq and AT2019nqc
  93. LIGO/Virgo S190814bv: No strong counterpart candidates in Swift/XRT observations
  94. GRB 190816A: Swift-XRT observations
  95. LIGO/Virgo S190814bv: DESGW candidate update
  96. LIGO/Virgo S190814bv: No candidates from image subtraction in DCT galaxy targeted search
  97. LIGO/Virgo S190814bv: WIRC NIR imaging follow-up of DECam transients
  98. LIGO/Virgo S190814bv: Keck/MOSFIRE NIR spectroscopy of DG19njmjc (= AT 2019nra)
  99. LIGO/Virgo S190814bv: DG19dnjlc is not offset from its host galaxy
  100. LIGO/Virgo S190814bv: Additional candidates identified in DECam images by the DECam-GROWTH team

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